Permissive /restrictive ROE
I had this explained to me by a former A-6 Sqn commander who said that the USAF worked to "if it hasn't been specifically authorised, it's forbidden" whereas the USN worked to "if it hasn't been specifically forbidden, use your judgement and be prepared to give it a go".
He cited escorting a badly damaged B-52 which was leaking vital fluids all over the place back from a raid over N. Vietnam and trying to persuade the young man driving it to follow him back to his base. The lad said he couldn't divert to that base because he hadn't been authorised to go there. The long and the short of it was the B-52 crashed with the loss of all on board trying to make his authorised destination. My informant was vitriolic in his condemnation of the USAF system controlled from SAC by as he put it "Monday morning quarter-backs left over from Korea"
The Ancient Mariner